Which feature is essential for a rotor-based UAS?

The essential feature for a rotor-based UAS is propellers. Rotor-based unmanned aerial systems (UAS), commonly known as helicopters or drones with rotors, utilize propellers to generate lift and enable vertical flight. The design and operation of these systems rely fundamentally on spinning blades that create the necessary aerodynamic lift to support the aircraft in the air, allowing it to ascend, descend, and maneuver with agility.

Wings are typically associated with fixed-wing aircraft that require forward motion to generate lift through aerodynamic forces, which is not the case for rotor-based systems. Jet engines are a propulsion technology primarily used in jet aircraft that operate at higher speeds and altitudes, which do not apply to the mechanics of rotorcraft. A fixed structure does not constitute a critical feature of rotor-based UAS, as these systems are designed to be agile and typically have moving parts that allow for various flight dynamics.

Thus, the use of propellers is essential for rotor-based UAS to function effectively in their intended applications, providing stability, control, and the ability to hover.